The potential discomforts and risks in part 2 are the same as those in part 1. Repeated blood 
sampling and gene insertion could result in the repeated exposure of a single -lymphocyte to 
additional gene insertion events. Part 2.B. will end after the patient has received 
approximately 6 infusions of autologous T cells at a dose/infusion calculated to be roughly 
equivalent to the weekly dose of PEG-ADA (15 U/kg). Four weeks after the last infusion, a 
thorough immunologic evaluation will be performed as will an estimate of the persistence of the 
gene-modified cells in the patient’s blood. If no evidence of immunologic benefit from parts 1 
and 2 are shown and if less that 1% of the blood lymphocytes represent persisting infused cells, 
the intravenous infusions of the patient will cease. The patient will then be treated with a 
modified protocol using intraperitoneal cell injections for approximately 6 infusions at a cell 
dose of 2-5x1 0®/kg. With clear evidence of immunologic benefit, periodic Infusions of ADA 
gene-modified autologous T cells will be continued indefinitely. The benefits of part 2 could 
include significant immunologic improvement for the patient. We should also learn important 
information concerning the effects of repeated infusions (as opposed to single infusions) of 
substantial numbers of autologous ADA-corrected T cells on the survival of those T cells in 
vivo. Part 2 should last from 12 to 18 months and will require about 12 patient visits to the 
Clinical Center. 
If this gene correction protocol does not prove to be superior to PEG-ADA alone, the protocol 
will be retired. If this treatment protocol proves to be superior to PEG-ADA alone, we will 
continue to indefinitely offer periodic infusions of ADA gene-modified T cells along with PEG- 
ADA treatment. 
The NIH will provide the PEG-ADA and any IVIG required during the period of participation in 
this study and will continue to provide these drugs after completion of the protocol in order to 
maintain close follow-up of each patient indefinitely. If the therapy proves to be beneficial, we 
will continue to offer infusions of ADA gene-modified lymphocytes indefinitely. 
8.0 Study Parameters 
8.1 Evaluations Following Each Cell Infusion 
Eighteen to 72 hours after completion of each treatment blood will be obtained for; 
a. CBC, differential, platelets 
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Recombinant DNA Research, Volume 14 
